Portion of a lamp structure



FIG. 1 is a front view of a portion of a lamp structure showing my new design;

FIG. 2 is a rear view thereof;

FIG. 3 is a left side view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a top plan view thereof;

FIG. 6 is a bottom plan view thereof; and,

FIG. 7 is a perspective view thereof.

The broken lines showing in Figures are for illustrative purposes only and form no part of the claimed design. 

CLAIM The ornamental design for a portion of a lamp structure as shown and described. 